RFR: 8318328: DHKEM should check XDH name in case-insensitive mode

[Weijun Wang]

The comparison should have been done in case-insensitive mode.

The new test confirms the change inside `DHKEM.java`. The one in `XDHPrivateKeyImpl.java` is not easy to confirm. The SUN provider's implementation always got the name "correct".

-------------

Commit messages:
 - the fix

Changes: https://git.openjdk.org/jdk/pull/16225/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16225&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318328
  Stats: 66 lines in 3 files changed: 63 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/16225.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16225/head:pull/16225

PR: https://git.openjdk.org/jdk/pull/16225